noun: (linguistics) A phoneme, morpheme, or word shared by two languages or dialects, via cognation or naturalization.
noun: (biology, genetics, medicine) One of a group of similar DNA sequences that share a common ancestry, or the peptides or proteins that they encode; the counterpart gene or protein in another taxon evolved from a common ancestor (molecularly it may be either identical or similar).
noun: (organic chemistry) A member of a homologous series.
noun: (cultural anthropology) A belief, practice, concept, or artifact that has a counterpart in another culture.